A tired sequel to the comic sci-fi franchise about two special agents (Will Smith and Tommy Lee Jones) who hunt the aliens among us. They go back in time, allowing Josh Brolin to give a funny impersonation of a young Jones, but the franchise is beginning to show its age.

Starring: Will Smith, Tommy Lee Jones, Josh Brolin

Rating: Two and a-half stars out of five

When Men in Black was released in 1997, it had an ingenious charm in its notion of a group of anonymous special agents who kept track of the intergalactic aliens among us -- and we all know some -- and the matter-of-fact tensions between energetic Agent J (Will Smith) and his cantankerous partner Agent K (Tommy Lee Jones).

By the 2002 sequel, the charm had faded, not to mention the novelty. Now, a decade later (and a nickel short) comes Men in Black 3, in which Agents J and K go back in time to save the world. What they can't do, unfortunately, is go back and save the franchise.

Men in Black 3 is a tired retread, even though the original material has a few miles left on it. It benefits mostly from the performance of Josh Brolin as the Young Agent K, an impersonation that captures Jones in his essence: the voice, the mannerisms and the seeds of the crankiness to come. Tommy Lee himself -- one of the premiere irritable personalities of the screen -- appears only briefly in what amounts to an extended cameo. For the record, he is aging into a morose leatheriness: he looks like the world's unhappiest catcher's mitt.

The film starts with the escape from a lunar prison of Boris The Animal ("It's just Boris," he tells everyone who uses the extended name), an alien criminal with claws that pop alarmingly from everywhere on his body and a pair of goggle eyes. He's not the most inventive character in the Men in Black series, but as played by Jemaine Clement (The Flight of the Conchords), he's one of the snarliest.

Boris has been in jail after being captured 40 years ago. In order to escape this fate, he finds a time machine, returns to 1969 and kills the young Agent K who arrested him. It's up to Agent J to follow them back in time and straighten out history.

The trip begins with a comically vertiginous jump of the Chrysler Building -- the effects in Men in Black 3 have a loopy appeal -- and a crash landing into an America of hippies, men in fedoras, and convertible Cadillacs the size of land yachts. However, the movie doesn't do very much with the possibilities of culture clash beyond one memorable scene where Agents J and K visit The Factory where Andy Warhol (Bill Hader) is host of a happening that looks very much like an alien housewarming.

It's a sly joke in a film that doesn't know what to do with its notions of fractured time. Shooting started before the script was completed, and what's on screen has the feeling of something rigged up as a kind of platform for the special effects: the fish-themed aliens in a Chinese restaurant, the man with a bowling-ball-sized head who runs into some trouble in a bowling alley, as well he might. These have become the signature pieces of the Men in Black series, but their appeal has become nostalgic: we like them mostly because they remind us of the clever surprises of the earlier films.

Director Barry Sonnenfeld, who has made all three movies, keeps things light and bubbly -- well, as light and bubbly as things can get in a Tommy Lee Jones film -- but Men in Black 3 seems to lose steam as it huffs and puffs to its silly conclusion. There's a sentimental twist at the end that it doesn't bear thinking about because, in retrospect, it kind of adulterates the first one.

In a movie about time travel, it's worth noting that Smith doesn't seem to have aged a day, and the new boss of the division is played by Emma Thompson, who is beginning to look like Julie Andrews, although this could be another special effect. There's also a lovely turn by Michael Stuhlbarg (A Serious Man) as an alien named Griffin who sees all futures unfolding at once. Possibly there's a better one out there.